A pelvis contains a sacrum and a pair of ilia connected to right and left sides of the sacrum. The ilia are connected to the sacrum by a pair of sacroiliac joints located at a bottom end of a lumbar. The sacroiliac joints serve as firm joints, surrounded by ligaments, while the joints allow slight motions of several millimeters. The slight motions of the sacroiliac joints help a human body to keep a balance depending on various body motions in daily life. Thus, the sacroiliac joints support the lumbar at the bottom thereof.
When a load is placed on the sacroiliac joints during an unnatural body motion such as a work in a stooping position, the load may cause a slight displacement in the sacroiliac joints such as loosening and twisting thereof. The slight displacement may induce a change in a position or an angle of the pelvis, which directly supports the bottom of the lumbar. Typical examples of the change in the position or the angle of the pelvis include pelvic abnormalities such as “anteversion” and “retroversion”.
The changes in the position or the angle of the pelvis may hinder proper support for the lumbar by the sacroiliac joints, and thus may cause a damage to the sacroiliac joints such as a lower back pain. The damage in the sacroiliac joints may become a cause of a chronic lower back pain if the damage persists without reduced. Further, a damage in the sacroiliac joints caused by loosening thereof is often regarded as relating to a lower back pain of a woman after giving birth.
To solve the problems, various types of sacroiliac belts for protecting the sacroiliac joints, which are also referred to as waist corsets, waist supporters, sacroiliac correction belts, or pelvic protection belts, have conventionally been proposed.
For example, PTL1 discloses a waist corset comprising a fixing portion and a belt portion. The fixing portion has a large width, and is worn on a user's belly. The belt portion extends from the fixing portion, and is wound around the user's waist. Ends of the belt portion can be bonded to the fixing portion via touch fasteners.
PTL2 discloses a belt for correction of movement in sacroiliac joint capsules. The belt has an adjustable length to be wound around a user's waist, having a part made of an elastic material. The belt has a pressing member on an inner surface thereof at a position which is in contact with an area between the user's posterior superior and inferior iliac spines when the belt is wound around the waist at a specific height corresponding to the ilia.
Further, PTL3 discloses a lumbar belt comprising a main belt, a pair of fastening belts, and a hanging belts. The pair of fastening belts helps fastening of the main belt when the main belt is wound around the waist. The hanging belts extend upward from the main belt like suspenders, and maintain the position of the main belt around the waist even when the main belt is not fastened.